Those descriptions would be sufficient if you were also more explicit about /s and /m. Explaining that they mean singleline and multiline respectively doesn't really help newbies remember which is which or what each of them does. Heck, if uri hadn't taught me the mnemonic that /s changes a Single metacharacter (i.e. .) whilst /m changes Multiple metacharacters (i.e. ^ and $), then I still wouldn't be able to remember which is which myself!